Field devices are already known from the prior art that are used in industrial installations. Field devices are often used in process automation, as well as in manufacturing. Field devices, in general, refer to all devices which are process-oriented and which supply or process process-relevant information. Field devices are thus used for detecting and/or influencing process variables. Measuring devices, such as sensors, are used for detecting process variables. These are used, for example, for pressure and temperature measurement, conductivity measurement, flow measurement, pH measurement, fill-level measurement, etc., and detect the corresponding process variables of pressure, temperature, conductivity, pH value, fill-level, flow, etc. Actuators are used for influencing process variables. These are, for example, pumps or valves that can influence the flow of a fluid in a pipe or the fill-level in a tank. In addition to the aforementioned measuring devices and actuators, field devices are also understood to include remote I/O's, radio adapters, or general devices that are arranged at the field level.
A variety of such field devices are produced and marketed by the Endress+Hauser group.
In modern industrial plants, field devices are usually connected via communications networks, such as fieldbuses (Profibus®, FOUNDATION® Fieldbus, HART®, etc.), to higher-level units. Higher-level units are control units, such as an SPS (storage programmable controller) or a PLC (programmable logic controller). The higher-level units are used for, among other things, process control, as well as for commissioning of the field devices. The measured values detected by the field devices—in particular, by sensors—are transmitted via the respective bus system to a (or possibly several) higher-level unit(s) that further processes the measured values, as appropriate, and relays them to the control station of the plant. The control station is used for process visualization, process monitoring, and process control over the higher-level units. In addition, a data transfer is required from the higher-level unit via the bus system to the field devices—in particular, for configuration and parameterization of field devices, as well as for control of actuators.
The functional scope of modern field devices that are produced and marketed by the applicant includes the so-called “heartbeat” technology. This diagnostic method allows information to be collected that permits conclusions about the correct function or about the accuracy of a field device, or of its components. This currently includes, in particular, the measurement function of the field device and the correct operation of its transmitter electronics. In this context, the field device creates a status message periodically or at other appropriate instants that includes information about the “device health.”
Within the meaning of the German term, “Sicherheit,” which in the American equivalent includes the meanings of “security” and “safety,” only the “safety” part is covered by the field devices known in the prior art.
The term, “safety,” can be generally described by the term, “accident prevention.” For this purpose, functions are implemented in field devices that protect people in the area surrounding the field device and the environment of the field device itself. For example, certain field-device housings are specially designed in order to permit safe operation of the field device in potentially explosive environments of a plant.
The term, “security,” indicates the prevention of tampering with field device by third parties. It is sought in this manner to protect a field device from being able to be sabotaged by an unauthorized party, or from security functions, for example, being able to be switched off and/or device parameters of the field device to be changed through unauthorized intervention.
In particular, an unauthorized party is, therefore, currently not prevented from installing a “fake” device in the plant that, from the viewpoint of the control system, behaves exactly like a correctly functioning field device and therefore cannot be distinguished from an authentic field device.
In addition, while the heartbeat technology known from the prior art in fact includes information on device function, possible error sources are, however, not discovered that may arise because of erroneous or deliberate tampering with device parameters.